There have been many efforts to provide improved combinations of processability and physical properties in carbonate polymers and other engineering thermoplastic resins. For example, in U.S. Pat. Nos. 5,171,824 and 4,708,994 and copending application No. 894,033 it is taught to incorporate reactive arylcyclobutene groups. Such resins are then crosslinked and cured during a subsequent heating step and shown to be more solvent and heat resistant.
In published Japanese Patent Applications 63-003,023 (1988) and 63-015,821 (1988) it is disclosed that carbonate polymers can be provided with isopropenyl end groups by the use of isopropenyl phenol as a carbonate polymer chain terminating agent. The disclosed polymers are taught to be used as reaction-type resin modifiers, additives or raw materials for the manufacture of copolymers.
In U.S. Pat. No. 4,912,914 it is proposed that crosslinked or branched polycarbonates can be prepared by incorporating a diester diphenolic monomer into the carbonate polymer backbone, then heat activating the crosslinking reaction. However, since the crosslinking reaction causes the polymer backbone to be cut at the point of crosslinking, the polymers that are taught would be expected to have undesirable levels of low molecular weight and high molecular weight (gel) byproducts.
In U.S. Pat. Nos. 3,770,697 and 3,652,715 carbonate polymers are provided with thermally activated, unsaturated imido groups to prepare functionalized, curable polymers. Upon heat activation, the resulting addition polymerization provides a crosslinked, high molecular weight component. Unfortunately, however, it is difficult to incorporate such unsaturated imido-functional groups in carbonate polymers in standard, interfacial carbonate polymer production processes due to the nitrogen-containing imido groups that must be incorporated and, upon attempting to process and cure such polymers, it is found that they are thermally unstable.
U.S. Pat. No. 4,943,619 discloses a polycarbonate-epoxy copolymer which is formed by reacting the epoxide groups of an epoxy resin with in-chain carbonate groups of a carbonate polymer in the presence of a catalyst. Through the reaction of diepoxides and polycarbonates, three dimensional crosslinked networks can be formed. However, since the crosslinking reaction causes the polymer backbone to be cut at the point of crosslinking, the polymers that are taught would be expected to have undesirable levels of low molecular weight and high molecular weight (gel) byproducts.
In addition, there are a number of known crosslinked carbonate polymer compositions of a curable or thermoset nature based on epoxide, acrylic and other types crosslinking techniques. See for example U.S. Pat. Nos. 5,037,903; 4,255,243 and 5,047261; and Japanese Patent Publications JP 63-270,641; JP 01-024,809; JP-01-075,521 and JP 01-054,058.
However, due to deficiencies such as poor reactivity of the curable resin, thermal instability during and after curing, and insufficient hardness, chemical resistance, adhesion and/or optical properties, carbonate polymers having improved combinations of these properties are continually being sought.